I knew you wouldn’t abandon your fans. As a longtime admirer, I’m delighted that you will be moderating another presidential debate, on October 3rd — the first one, between Mitt Romney and Barack Obama. Topic: Domestic policy. This will be your 12th turn as presidential debate moderator. Wow.

I’m writing to ask that you put Global Warming on the debate docket. So far, neither candidate is saying a word about it. Yet dangerous climate change is one of the most important crises facing our nation, and indeed, our world. But as with most grave situations, it comes with enormous opportunity for moving the country into the forefront of new technologies and economic strength.

We are at a turning point in history. If we do not show leadership in cutting carbon and methane emissions, we will lose our moral authority in global affairs, to say nothing of imperil life on Earth. If we do not launch a massive, national Race to Clean Energy — mobilizing our best engineering minds — we stand to lose our position as a global leader in scientific and technological innovation.

We don’t need to hear another cartoonish conversation about whether climate change is “real” or whether the science is “believable.” We need you to cut to the chase. The way we deal with climate pollution has a huge impact on our economy, on jobs, on innovation, on future growth. Ask the candidates: What is our energy future? What’s the best way to get there? How can we be more efficient with precious energy resources?

How do we clean up pollution that is damaging the health of our families?

I grew up under your tutelage, Jim Lehrer. For decades, in the 70s, 80s, and 90s, yours was among the most trusted names in television journalism. It is hard to remember back to a time before the Internet, but I well remember when the only serious analysis of important news we could find was during your hour on PBS. You shaped — and inspired — an entire generation of viewers. You cared about what counted. You showed us how to ask the questions that get to the heart of a matter.

You still do.

You are a father, and a grandfather. You must be thinking about the condition of the world they will inherit. Please, Mr. Lehrer, use your position to ask the candidates a question about a subject both are avoiding, for the worst reasons. You’ve got the best reasons in the world to do so: all the fans who count on your leadership — and your six grandchildren.